title: Phases in the (1 - x)Na₀.₅Bi₀.₅TiO₃-(x)CaTiO₃ system.
abstract: The structures of (1 - x)Na(0.5)Bi(0.5)TiO(3)-(x)CaTiO(3) at room temperature have been investigated using neutron powder diffraction and dielectric studies. The system exhibits an orthorhombic (Pbnm) structure for x ≥ 0.15 and rhombohedral (R3c) for x ≤ 0.05. For x = 0.10, though the neutron diffraction pattern shows features of the orthorhombic (Pbnm) structure, Rietveld refinement using this structure shows a drastic reduction in the in-phase tilt angle (∼4°) as compared to the corresponding value (∼8°) for a neighbouring composition x = 0.15. The neutron diffraction pattern of x = 0.10 could be fitted equally well using a two-phase model (R3c + Pbnm) with orthorhombic as the minor phase (22%), without the need for a drastic decrease in the in-phase tilt angle. The dielectric studies of x = 0.10 revealed the presence of the polar R3c phase, thereby favouring the phase coexistence model, instead of a single-phase Pbnm structure, for this composition.
authors.affiliation: Department of Materials Engineering, Indian Institute of Science, Bangalore 560012, India. rajeev@materials.iisc.ernet.in
authors.forename: Rajeev
authors.initials: R
authors.lastname: Ranjan
authors.forename: Rohini
authors.initials: R
authors.lastname: Garg
authors.forename: V
authors.initials: V
authors.lastname: Kothai
authors.forename: Anupriya
authors.initials: A
authors.lastname: Agrawal
authors.forename: Anatoliy
authors.initials: A
authors.lastname: Senyshyn
authors.forename: Hans
authors.initials: H
authors.lastname: Boysen
mesh_terms: D001729:Bismuth / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry; D017601:Oxygen Compounds / Q000737:chemistry*; D044367:Phase Transition; D017670:Sodium Compounds / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D009930:Organic Chemicals; D017601:Oxygen Compounds; D017670:Sodium Compounds; C071334:calcium crimson; D014025:Titanium; D001729:Bismuth